The present invention relates to synchros, more particularly to methods and apparatuses for converting a synchro's analog signals to digital signals, or vice versa.
Synchros are analog electronic devices that have been used for many years, primarily in military contexts, for providing angular, positional, and other information pertaining to navigation, communication, detection, weaponry, etc. Examples of information provided by synchros are changes in course, speed, and range of targets or missiles, and angular displacement (position) of a ship's rudder. The noun “synchro” derives from the adjective “synchronous.” The synchro was originally developed during the Second World War to synchronize movements of a gun turret with those of a control dial. Generally speaking, synchros look like electric motors (insofar as including a rotor, a stator, and a shaft) and operate like rotary electrical transformers.
Literature instructive on synchros includes, for instance, the Synchro/Resolver Conversion Handbook, Fourth Edition, 1994, Library of Congress Catalog Number 74-77038, Data Device Corporation (DDC), 105 Wilbur Place, Bohemia, N.Y. (electronic version, 125 pages, available in pdf at DDC website: http://www.ddc-web.com).
Synchro-to-digital conversion—that is, conversion of synchro (analog) signals to digital signals—is necessary in order for computer technology to make use of analog signals transmitted by synchros, which represent older technology. Conventional practice, such as onboard United States Navy ships, has involved interfacing of synchro-based systems with modern computer-based controls through implementation of centralized computer units. However, the computer systems utilized for such purposes are large and expensive and do not permit direct interfacing of synchros with common smaller-scale digital equipment such as programmable logic controllers (PLCs) or embedded devices, or with popular networking protocols such as DeviceNet.
The following United States patents, each of which is hereby incorporated herein by reference, are of interest with regard to conversion between synchro data and digital data: Goode, III et al. U.S. Pat. No. 6,222,469 B1 issued 24 Apr. 2001; Nealy et al. U.S. Pat. No. 6,172,627 B1 issued 9 Jan. 2001; Gwin U.S. Pat. No. 6,069,576 issued 30 May 2000; Woodland et al. U.S. Pat. No. 5,646,496 issued 8 Jul. 1997; Howard et al. U.S. Pat. No. 5,173,696 issued 22 Dec. 1992; Deppe et al. U.S. Pat. No. 5,034,743 issued 23 Jul. 1991; Hermansdorfer et al. U.S. Pat. No. 4,430,640 issued 7 Feb. 1984; Hermansdorfer et al. U.S. Pat. No. 4,401,932 issued 30 Aug. 1983; Simon et al. U.S. Pat. No. 4,281,316 issued 28 Jul. 1981; Stack et al. U.S. Pat. No. 4,375,636 issued 1 Mar. 1983; Chasson et al. U.S. Pat. No. 4,216,466 issued 5 Aug. 1980; Simon et al. U.S. Pat. No. 4,164,729 issued 14 Aug. 1979; Freed et al. U.S. Pat. No. 4,062,005 issued 6 Dec. 1977; Aramaki U.S. Pat. No. 4,017,846 issued 12 Apr. 1977; Games et al. U.S. Pat. No. 3,997,893 issued 14 Dec. 1976; Griffin U.S. Pat. No. 3,993,993 issued 23 Nov. 1976; Domchick et al. U.S. Pat. No. 3,618,073 issued 2 Nov. 1971.